1. Field of the Invention
The present invention relates to free-cutting machine tools of the boring mill type, and more particularly to an eccentric positioning device for tools, workpieces, and measuring instruments which is also adaptable for rotation of a tool or workpiece around different rotational axes.
2. Description of the Prior Art
The field of free-cutting machine tool technology offers an almost unlimited variety of configurations for the positioning of tools, workpieces, and measuring instruments, in relation to one another and for rotary motion or straight-line motion of either the tool or the workpiece, or both. The type of machine tool which is to be replaced by the device of the present invention commonly uses a moving tool which is carried on a faceplate equipped with a radially adjustable faceplate slide, the radial adjustment being normally performed by hand, using a threaded adjustment spindle. The faceplate itself is carried on the end of a horizontal main spindle which is rotatably supported in a heavy headstock. A workpiece which is to be machined may be mounted directly on the base plate of the machine tool or it may be carried on top of a horizontally adjustable carriage consisting of either a simple longitudinally adjustable table or a cross slide offering two axes of horizontal movement. Depending upon the particular machining operations necessary, additional adjustable supporting means may be provided, in order to obtain angular adjustments of the workpiece in the direction of either roll, pitch, or yaw, for example.
These known machine tools have various shortcomings, most notable among them being a rather high specific load on the bearing surfaces, depending upon the adjustment configuration. These bearing surfaces are also very prone to becoming soiled. The relative positioning between the workpiece and the tool requires separate adjustments on two cross slides and on the faceplate slide along separate straight-line guides which are frequently only moderately rigid. The accuracy of guidance on these straight-line guides is subject to variation, depending upon the amount of load applied against them. Consequently, the machining accuracy of the known machine tools of this type is subject to variations and it is therefore inadequate for a variety of purposes.